TAXONOMY.-The subgenus includes
three species.One species, Cecilioides consobrinus, is widespread
in the American tropics, and consists of several subspecies.The typical subspecies occurs in Cuba. Another
subspecies, C. c. primus, is found in
Mexico and Central
America.

TAXONOMY.-There is a tendency in
current literature to disregard subspecies, and cite only species names, which
automatically take on the name of the typical subspecies.It is presumptive of later workers to assume
which subspecies was intended.Such is
the case with the work by Pérez & López (2002).However, I am not aware of any authentic
identifications of Cecilioides
consobrinusconsobrinus in the
study area.

Family SUBULINIDAE Fischer & Crosse, 1877

DISTRIBUTION.- Tropical America east through Africa and southeast Asia.

TAXONOMY.-Numerous genera.

Subfamily SUBULININAE
Fischer & Crosse, 1877

Most
Middle American Subulinidae had been grouped in the genus Leptinaria. A species critical to this classification was Allopeas gracilis (Hutton, 1834), which
was placed variously within Opeas and
then Lamellaxis, which in turn was
considered a subgenus of Leptinaria.H. B. Baker (1927, 1935, 1945) pointed out
the anatomical differences between Opeas,
Beckianum, Allopeas, Leptopeas, Lamellaxis and Leptinaria.The anatomies of
only a few species among these genera were known.Authors continued to unite most of the Middle
American species within Leptinaria
because of the lack of discrete shell differences between it and Lamellaxis, Leptopeas and Allopeas.This classification recognizes Opeas, Allopeas, Leptopeas, Lamellaxis, Beckianum, as separate genera because of their known anatomies.

DISTRIBUTION.-Tropical,
subtropical and many temperate regions of the paleotropical regions of the
world.Allopeas gracilis and a few closely related species are readily
dispersed elsewhere through human activities.

TAXONOMY.-Several species.Conventionally, Allopeas had been treated as a subgenus of Lamellaxis.More recently it
is recognized as a separate genus because of its anatomical dissimilarity with Lamellaxis and other genera.

DISTRIBUTION.-This is a tropical
American genus which is distributed from Mexico south to Bolivia.

TAXONOMY.-Twenty-one species and
five subspecies occur in the study area.Other species occur in South America.The arrangement of species given below follows Von Martens (1898) and
Pilsbry (1907).Formerly most of the
species were placed in Leptinaria,
subgenus Lamellaxis.Data provided by H. B. Baker (1927c. 1945)
necessitate the recognition of Lamellaxis
as a separate genus.These non-lamellate
Mexican and Central American species form a cohesive group of similar appearing
species.Lamellaxis lacks a parietal lamella, and the outer lateral teeth of
the radula are tri-cuspid, where-as Leptinaria
has a parietal lamella at some stage of development, and the outer laterals are
bi-cuspid.

DISTRIBUTION.-Worldwide in
tropical, subtropical and many temperate regions of the world.Some species are readily transported through human
activities, which account for much of the distribution of the genus.

TAXONOMY.-Numerous species.The exact number is uncertain because many
included species are known only from shells, and no doubt anatomical
investigations will change their classification.Three species are known from the study area.

TYPE LOCALITIES.-Helix octona: probably South
America.The species was
already widely disseminated by humans long before it was studied by
naturalists.Achatina trochlea: Mexico.Subulina
octona var. strebeli: Cd.
Campeche, Campeche.

Family SPIRAXIDAE
H. B. Baker, 1939

The
classification of the family follows H. B. Baker, 1939b, 1941a, 1941b and
1943a.Three subfamilies, representing
258 species an an additional 40 subspecies, are recognized in Mexico and Central America.Most species are very restricted in their
distributions, reflecting a high degree of local endemism.The majority of the species are known from
only a few regions of the study area.This is a reflection of its early colonial history with limited
accessibility into many o the regions, and the very small number of
malacologists who have worked there.Large areas of the study area remain very poorly surveyed, and
undoubtedly the number of spiraxid species will be vastly increased with
further biodiversity surveys of the many biotic provinces that comprise Mexico and Central America.Even areas that are relatively well known,
such as central Veracruz,
yield new taxa with each additional investigation.

Subfamily EUGLANDININAE H. B. Baker, 1941

Euglandinarum H. B. Baker, 1941; Nautilus, 55: 54.

DISTRIBUTION.-Southeastern
United States south through Mexico
and Central America to Peru,
Bolivia
and French Guyana.The subfamily is
absent from the West Indies except for coastal islands such as Cozumel, Utila,
Corn Island, etc.

TAXONOMY.-The subfamily
Euglandininae includes five genera.Currently 110 species are recognized in Mexico and Central America.

TAXONOMY.-Twenty-one species and
four subspecies are recognized.Cosmomenus, which is treated as a
separate subgenus, was described at a section of Singleya on the basis of the origin of the penis retractor
muscle.In Singleya the penis retractor originates on the inner wall of the
lung.In Cosmomenus the penis retractor originates on the left side of the
columellar retractor muscle.The
assignment of species to either subgenus on the basis of shell characters is
arbitrary.Most of the following species
are known only on the basis of the shell.They are place in Singleya
because it is the senior name.

TYPE LOCALITY.- Among boulders in an open semi-xeric scrub forest on a
limestone hillside, on the west side of the Rio Tehuántepec, 25 km NW of the
Presa Benito Juaréz (dam), Oaxaca, Mexico; 300 m alt.Holotype FLMNH 34691.

DISTRIBUTION.—Mexico, Central
America, and Cuba.A single species is
reported from Venezuela.

TAXONOMY.—Fifty-five species and
fourteen subspecies are recognized in Mexico and Central America.Four subgenera, Streptostyla, Chersomitra,
Peténiella and Eustreptostyla, occur in the study area.Another subgenus, Rectoleacina, occurs in Cuba.

The distinctions between the
subgenera Streptostyla and Chersomitra are anatomical
primarily.The numerous species that
remain unknown anatomically are retained in the subgenus Streptostyla, with the exceptions of those placed in Eustreptostyla and Peténiella.Species for
which the anatomy is known are preceded with an asterisk (*).Within Streptostyla
species are grouped according to shell shape as a matter of convenience only
following von Von Martens (1892) and Pilsbry (1897).The arrangement does not reflect phylogenetic
relationships, which is not possible to achieve without further anatomical or
genetic information.

DISTRIBUTION.-Northeastern Mexico from Tamaulipas and San
Luis Potosí south to Central Veracruz.

TAXONOMY.-Five species and two subspecies are recognized.The shell of Eustreptostyla is characterized by having a strongly twisted
columella and having strong growth threads below the suture. The type species
is large with a thick, solid shell about 30-40 mm high.

Subfamily SPIRAXINAE H. B.
Baker, 1939

DISTRIBUTION.- Spiraxis is
confined to the West Indies.The
subgenera Spiraxiss. s., Repressaxis H. B. Baker, 1939, Dignaxis
H. B. Baker, 1939 and Euspiraxis
Pfeiffer, 1854 are known from Jamaica and Hispaniola.The subgenus Ravenia Crosse, 1873 is confined to Los Roques.All mainland species are referred to
different genera.

TAXONOMY.-Five genera and
seventy-five species of Spiraxinae are recognized in the study area.

Traditionally Spiraxis has been used as an all-inclusive genus for species of the
Spiraxinae because of the difficulty of assigning species to different genera
on the basis of shell morphology. H. B. Baker (1939b) discusses the anatomy of
the subfamily. He emphasizes that subgenera and sections he recognized should
more properly be ranked as genera and subgenera on the basis of anatomical
differentiation. This ranking was followed by Zilch (1960) and is adapted here.
The large number of species assigned to Volutaxis
and Pseudosubulina remains arbitrary
in many cases because of the lack of anatomical information.

Genus Mayaxis Thompson, 1995

Mayaxis Thompson, 1995; Bull. Fla. Mus.
Nat. Hist., 39: 79-81.

TYPE SPECIES.-Myaxis leei Thompson, 1995.

DISTRIBUTION.-Chiapas and Tabasco,
Guatemala and northern Honduras.

TAXONOMY.- Nine species are placed in the genus.Previously, three species, Myaxis cilindrella, M. porrecta and M. stolli
were classified as Subulina. They are now placed in Myaxis on the basis of shell morphology and for biogeographic
reasons